The present invention relates to a side terminal for use in conjunction with electrical storage batteries, and in particular relates to an alloy for the formation of such a side terminal.
Side terminal-type batteries generally include a battery case which has thereinside a plurality of individual cells which are separated by a series of partition walls. These cells are adapted to contain a plurality of battery elements therein. The battery elements are connected to each other in series by either connection through the partition walls or over the top of the walls. The end-most battery elements (i.e., the elements in the two end cells) are further connected to terminals which extend through the sidewall of the battery case. To use the battery, electrical connections are made with the battery terminals by positioning a cable connector against marginal portions of the terminal. Generally, the terminal has a threaded opening in the center thereof and the cable connector is retained in place against the terminal by using a bolt or similar threaded device which extends through the cable connector and engages the threaded portion of the terminal.
For convenience in construction, the side terminals usually become part of the battery case prior to the assembly of the various internal components which comprise the battery. To ensure a proper seal between the terminal and the battery case, the terminal is often directly cast within a cavity formed as part of the exterior surface of the battery case. Other times, the terminal is formed outside the case and later inserted into the cavity.
However the terminal is positioned in this cavity, it must be readily connectable to the end battery elements contained within the case. Oftentimes, resistance welding techniques are used to make this connection between the terminal and the battery elements. Therefore, the material for the terminal must be suitably selected with possible resistance welding in mind. In addition to considering a material suitable for resistance welding, the material must also be able to afford proper electrical connection between the battery element and the cable connector which will be connected to the terminal. These requirements necessitate that the terminal material exhibit sufficient conductivity for proper electrical performance and sufficient structural integrity to ensure a proper mechanical connection with the cable connector.
Because of these important requirements, prior workers in this art generally have been constrained to using side terminals formed only of lead, or a lead-antimony alloy, in combination with a threaded insert, such as a steel nut. The use of lead or the lead-antimony alloy helps to insure proper electrical performance, while the casting of the steel nut within the terminal helps to insure proper mechanical performance.
The actual conduction of electrical current takes place along the marginal portions of the terminal which directly contact the cable connector. Current flow does not proceed through the steel nut, which generally exhibits a substantial resistance. Therefore, the use of these steel nut inserts in addition to limiting current conductivity also prevents unnecessary limitations regarding cost and castability. Although the inserts are satisfactory for their purpose, it has become desirable to eliminate the need for such steel inserts.